Laminated spring.



- D LANDAU. Mmmm spams. APUCATION HLED IAN.30,1915. Patented Sept HEME* z SHEETSAHEH 2.

' WiTNEssEs v V Q IN1/Emea M 4 l l' /AJ B i* if //wa y AFTORNEY i DAVID LANDRAU', 0F NEW YORK, Y.

LAMAINATED SPRING.

Specication of Letters Patent.

. Patented sepeia, 1916.

Application ined January ao, 1915. serial No. 5,181.

To al?? whom it may concern.'

Be it known that I, DAvD LANDAU, a citizen of the United States, 'residing at 23 Mount lVforris Park west, county of Bronx, State of New York, have invented certain new and useful Improvements in Laminated Springs, of which the following, taken in connection with the accompanying sheet of drawings, is avfull, clear, and concise de-` scription thereof.

'The present inventionv relates'to certain new and useful improvements in the con struction of those' springs which are built up from a series of superposed leaves and are usually 'termed laminated springs, ther primary object of the invention being to provide a spring of this character'which embodies novel features of construction whereby dangerof failure by breakage of the master leaf'brought about by the fatigue of material is reduced to a minimum.

A further Aobject of the invention is to provide a spring of this character in which the initial internal tension produced in the spring leaves by banding or bolting the several leaves together when assembling the same is minimized, the spring being thereby enabled to have a much greater range of defiection. y

The invention still further contemplates the provision of a spring embodying the same principle of construction and designed to flex in opposite directions or take up the rebound in an effective manner without pijoducnig dangerous stresses in the master leaf p which is subjected to reversal stresses.

lVith these and other objects in view, the

invention consists in certain novel combinations and arrangements of the partsas will more fully appear as the description proceeds, the novel features thereof being pointed out in the appended claims;

For a full understanding of the invention, reference is to be had to the following derscription and accompanying drawings, in which,--v

Figure l is a sideielevation of anassem.

in accordance with the invention and embodying a slight modification. Figs. el, 5 and dare Similar views showing additional modifications. Fig. Tis aI side elevation of a spring constructed in accordance with the invention andv provided with a counterspring to take the rebound. Fig. 8 is a side elevation of a spring constructed in accordance with the invention and designed to flex iii opposite directions. Fig. 9, is a view showing the various leaves of the spring illustrated by Fig. 8 in the position assumed before being nipped together and clamped at their central portion. elevation of a spring designed to flex in opposite directions, but to resist a greater load in one direction than in the other direction, and Fig. 11A is a view showing the various spring leaves of the construction illustrated byxFig. 10 in the position assumed before being nipped together and clamped at their central portion.

Corresponding and like parts are referred to in the following description and indicated in all the views of the drawings by the same reference characters.

' In the art of maliing leaf springs it is customary to giveto the individual spring Fig. l0 is a side leaves different degrees of curvature, as

leaves are usually formed with the saine curvature. Vhen the spring leaves are nippedgtogether and clamped at their central point the master leaf is flexed in a negative direction, that is, in a direction opposite to that produced when the spring is acted upon by an external load. VVhei'e the master leaf is made of the same thickness or even of a thicker section than the shorter leaves, as is the more usual case, this initial negative stress in the master leaf produced bythe nipping or banding together of the spring plates, may be very considerable, and this negative stress or deflection must be counteracted by equal and opposite stresses ordeflections inl either all or some of the remaining spring leaves. 'When the spring is placed under a load and flexed in the i usual manner, the negative stress in the master leaf isfirst overcome and a positivevstress subsequently produced therein. The range of the stresses to which the main leaf or leaves are subjected thus includes both positive and negative stresses, and'it Ii's'an established fact that where the range of i'oo y stress is from tension to compression and This initial may "consequently A,be back again, failure of the metal from termed a negativestrgss, as opposed tc the fatigue may be expected niucli sooner than normal or ositive strana produced by. the would otherwise be the case. The safe action c f a` oad. However, by'changiu `the range of deflection is thereby decreased.. thickness of the master leaf 1 and ma ing Where the master leaf is made thicker or it thinner than the .other leaves,.the amount the same thickness as the remaining leaves,` of internal initial l'-iieg'ative reduced the initial internal negative stress produced therein is made comparatively Sina l so that therein by nipping the spr' g plates tothe spr' maybeexed over agreater range 1o getlier is comparatively large so that not without ear of vbrealring.t;he master leaf. only is the ability of the masterleaf to re- Furthermorgsince the. force or pressure re sist rebound decreased, but the range of the quired to hold'the master spring leaf 1 in strees from tension into compression and its flexed Vor distorted yposition after being back again as the springis loaded and unnipped must-be by equal and oploaded, is such as to render (he spring subposite stresses in the' other spring leaves, the lject to early failure by rupture brought reduction of the initialstrein the master about by the fatigue of the metal due to the leaf also results in a reduction of the initial large initial internal stress. In order to stresses in all ofthe leaves, thereby further avoid this difficulty and to reduce the initial increasing `they eliiciency of the spring as a zo internal stress caused by nipping it is whole so that `the spring will ast much-85 proposed to make the master leaf or leaves longer than` the conventional forms of thinner than the other leaves. springs nowA in ySuch a spring may bc ferring to Figs. 1 andl2, the numeral composed of several thinr'leaves comprising 1 designates the master leaf and 2 the short in effect the master leaf in combination with leaf, a series of leaves 3, 4 and 5 being intersuccessively shorter"leaves' thicker than the posed between the master leaf and the short thin leaf or leaves and either all of the same leaf. lThese several leaves are shown grad-V thickness, from the longer leaves to the ually thicker and shorter from the master shortest leaf, or, gradually increasingin leaf to the short leaf and the conventional thickness from the longer leaves to the 3o band 6 may be' provided for holding the shorter leaf, or several leaves may have the leaves together at their central point. Sevsagre thickness. Furthermore, thev leaves of eral of the longest leaves may, however, be the spring may be either tapered or not and of the same length, and likewise several the tapers may either be uniform or of may be of the same thickness as shown in gradually increasing lengths from the short- Figs. 3 to 6 inclusive. In fact, all but the est leaf upwardv to the longest leaf or even 10o master leaf or leaves may have the same vice versa. thicknessfthe master leaf or leaves being In Fig. 3 I have shown a form of the thinner. The individual leaves are initially spring` in which the numerals 10 and .1l formed with different degrees of curvature, designate two thin leaves which form in ef- 4o as indicated by Fig. 2, the master leaf 1 fect the master leaf, the leaf 10 being pro- 105 having a Smaller-degree 0f curvature than vided, at the ends thereof with conventional `the adjacent leaf and the degree of curvaeyes, 16. The successive leaves 12, 13 and ture increasing through the successive 14 darranged under the thin leaves 10 and 1l leaves, with. the exception of a few of the are all of the same. thickness a shorter leaves which may have the saine de-1 decrease in length f kree of curvature and fit closely together. 14 leaves 10 and 11 to the shortest s )ri leaf Vheio the number of plates is few, all leaves., 15. .The long leaf 1l is of equal lnu but may have different curvature. thicker than the individual lamina ofthe When the several leaves are nipped tomaster leaf and its ends are taiered while 5o gether and secured at their central point by the thicker leaves 12, 13, 14 and 15 are not 115 the band 6, or an equivalent device, the tapered, and the spaces between the endsof amount of the arch or camber of the inasthe leaves may either be of the saine length ter leaf 1'Iis increased, the ends thereof being or of gradually increasing lengths, measured deflectedin a direction away from the body 'from the master leaf downward to the short 5v5 f the spring While the central portion plate, as desired. As has been heretofore 120 ereof is deflected in an opposite direction, explained, by forming the master leaf of one Aor toward. the body of the spring. This or more thin strips, the negative stresses initial ileiring of the master leaf 1 1s directly produced therein by the flexing brought opposite in .sense and direction the .flexabout by the nipping operation are coni- 6Q\ ing produced therein when a load 1s applied paratively small so that the efficiency of the 125 tothe ends thereofv in the usual manner. In spring as a whole is increased and a greater other Words, the stresses produced in the range of deflection made possible, without y master leaf 1 by the nipping operation danger of the master leaf being caused toare exactly 'the reverse of the stresses prorupture because of initial stressv fatigue of e5 .duced therein under the action of a load. the metal. Sincegreater deflection implies 130 rom the longest Aspring greater loads, it follows then -that such springs can carry with equal safety greater loads. y

In Fig. 4 is shown a slight modification in which thelong spring leaves 10a and 11?M 112 are formed of thin material while the spring leaves 12a, 13%14CL `and 158L are formed are formedof thin material and of the same thickness, while the long leaf 112 and the leaves 12", 13", 14b and 15b gradually increase in thickness from the longer to the shorter leaf and have tapered ends. Also several of these leaves may have the same thickness. The conventional eyes 16b are provided at the ends of top leaf or lamina of the master leaf and a suitable clip, or band, or its equivalent 17b may be provided for holding the leaves together. The spaces between the ends of the spring leaves may be either of a uniform length or of a gradually increasing length measured from the nister leaf downward as found most desira` le.

Fig. G illustrates a, further slight modification in which 10c and 11c indicate two thin spring leaves constituting in effect a master leaf'. The next succeeding leaves 112, 12, 13c and 14c gradually, or rapidly increase in thickness, or several leaves may remain of the same thickness, while .the two shorter spring leaves 14 and 15c may be of the same thickness. Seats 16 are provided at the ends of the master leaf and a clip, or band, or its equivalent, 17c maybe provided for holding the spring leaves together at the center of the spring. In this construction the master lleaf is formed of 'several thin,

strips of material, a number of the shorter leaves are of the same thickness, while the following leaves gradually, or rapidly increase in thickness from the master leaf to the shorter leaves.

All of the various modifications shown by Figs. 3, 4, 5 and 6- operate 'in substantially the saine manner.l and have lthe added advantage, as has been explained, ofincreasing the possible range of defiection, rendering failure of the master leaf byfatigue improbable, and giving the spring increased ability to resist rebound.

The construction of a spring with a thin master leaf and thicker supporting leaves is disclosed in and forms a part of the subject-matter of my companion application,

vSerial No. 92,446, filedy April 20th, 1916, which is a continuation in part of a previous application, Serial No. 861,951, filed September 16th, 1914. The use ofthe thin master leaf is also covered broadly by the claims of mysaid application, Serial No. 92,446. For this reason, 1 do not claim this construction by itself herein but the present case relates to an adaptation of such" broad features of construction set forth in said application as used in connection with certain other features so as 4to produce a spring specially fitted for certain uses, particularly where the spring is required to withstand considerable deflections in opposite directions. As explained above, the capability of the spring to withstand reversal stresses due to rebound or'other defiection reversals is greatly enhanced by the use of a thin ,rnaster leaf, which also diminishes the initial' stresses due to nip. The ability to withstand reversal stresses may further be enhanced by the use of a counter spring or supplemental spring leaves, on the opposite side of the thin master leaf from the main supporting plates as will now be more fully described and it is to these features of construction that the invention forming the subject-matter of the present application more particularly relates.

Notwithstanding the increased ability of the spr-ing to resist rebound without danger of breaking thefniaster leaf, it may under some conditions be desirableto provide counter-springs, as indicated by Fig. 7. Where such counter-springs are used, however, they can be made of lighter material and more fiexible than has heretofore been the case, since a greater part of the force of the rebound may by this construction be taken 'up by the main spring master leaf.

Referring to Fig. 7, the numeral 20 designates the master spring leaf which is of thin material and the numerals 21, 22 and 23 the other spring leaveswhich may graduallylincrease in thickness and decrease in length from the master leaf to the short leaf. The counter-spring is arranged in a reverse order and includes the spring leaves 24, 25 and 26. A spacing block 27 is arranged between the` counter-spring .and the. main spring and the various members are held together by a suitable clip- 28, The main spring is lconstructed and designed to act in substantially the same manner as has been previously` explained in lconnection with the by the rebound they are/,brought into ,en"

gagement with the ends ofthe counterspring so as to bring the counter-'spring into master leaf which action. Ordinarily these counter-springs must be made strong and stiff, since the n? the muster leaf of the'main spring t rebound has been very greatly L- the 5 reduced by the comparatively large negative stresse-3 produced therein by the .nipping operation. With my construction, however, the ctl'c -ri\'e strength of the insister leaf to thc rebound is not greatly reduced by the negative produced by nipping und the counterspring muy accordingly be mede ighlcr und more iezrible. In other words, the of my main spring can reverse and dei; upwurdly with greater safety e than leaves of.a springs where the main leaves ere either thicker than or of equal thickness with the shorter leeres. There also frequently arises in the art the need `for a spring constructed to Hex in opposite directions under the seme or unequal loads. Such n spring will have the stress reversed in its main plate, where such ere used, and the most 'eiicient spring, therefore, is one in which the main plate, and clipped-,plate have e small, negative stress. The ordinary counterscting or rebound spring has :i very heavy main leaf and of necessity the negative stress produced therein by nipping7 is quite large, the result being 'that trouble is usually brought4 about by rupture of this master leaf. This difficulty may be eliminated by u construction such asis shown by Figs. 8

' and 9.4 The numeral 30 designates the thin is provided at the ends thereof with the usual eyes, or their equivalent, 31, Arranged upon opposite sides of 'the muster leaf 30 src the two sets ofsucl. cessively thicker und shorter leaves32, 33 and 34, each set of the leaves being identical since the spring is designed to carry sub# stantially the same loads in both directions. With the .exception of the master leaf 30, the various-leaves are individually bent, as indicated by Fig. 9, before assembling. -lVhen the .leaves are bolted 'together they Vnnatyfvlie.secured'aittheir central point by a suitble bolt 35. 'With u,l balanced spring such as is shown there will be no initial `stress put upon the muster leaf 30 und the nlasterlea will 'tl' lie-x in one direction as readily as in ti ppositedirection WithoutA difference of str s therein. With u thin muster leaf, however, 'the range of deflection is greater than with u thick master leef, lsince the same amount Kof deiiection producesY less stress in s thin leaf than in a *thicker one. Thd range of positive und negative stresses thus produced in the masterleaf is less for a-given amount of deflectipn thsn would .be required in a. thicker rupture from muster leaf, and thedanger of 'fatigue is thusdecresed. y: ,A "i `Where the spring; is designed-'tol take unf F55 loadslin. opposite?d1rectiosj-a, con:

`ind in all the clipped platesv struction such as is Shown by Figs. 10 and 11 may be used to advantage. The numeral 40 designates the master leaf which is provided with the usual eyes, or equivalent, 41, at. the ends thereof. Arranged' upon one side of the master leaf 40 vare the successively thicker and shorter Aspring leaves 42, 43 and 44, while arranged upon the opposite side of themaster leaf 40 are the opposed spring leaves 45 and 46; The spring leaves 42. 43 and 44 areA longer than. the spring leaves 45 and 46; these leaves aredesigned to coperute with the muster spring leef 40 to take the heavier load, the sprin leaves 45 Tund 46 in conjunction with the master leaf 40 taking the lighter and reversed load.

The individual spring leaves may have a preliminary curvature, as indicated by Fig. 11, although after being assembled they are nipped together and secured bythe conventional bolt or itsl equivalent, 47. The master leaf 40 is thus bowed less when. free, which puts an initial stress in it, said stress being 1n the direction of the upward-acting and small load. The initial internal stress produced by nipping thus decreases the strength `of the master leafI toresist the force ofthe lighter load, but by making the master leaf o thinnerL material this objection is reduced to e minimum. The stress produced in the thin master leaf by nipping?? and this has the advantage of enabling the spring tov be used .for a greater saying that one of the shorter leaves will usually breuk in advance of .the master leaf, thereby `giving warning of the fubt that the spring is vthe spring kre-A sults. *It has beenY attempted in the .past

With the above conis consequently muchsmaller than' would be produced in a thick muster leaf,

range ofiiexurey in both directions. This amountsy to' eater resilience 1'20 A 1n edaiifgerous condition before complete failure o to improv.: upon the conventional construcy*y tionr'of these springs b although such; y' und vhave nevelv rfully accomplished the eslred results.- ByIma gthe master leaf of thinner l me'terigd'tfli thev othery springs.Av are "more using better mg-`^`ffr c terial for the. muster les .than for theiothe'rj leaves,

leaves the range of deflection is increased, the danger of failure of the main leaf of the spring from fatigue of thel metal is reduced to a minimum, the ability of the springto resist rebound increased, and a construction provided which has great re-l silience and will safely carry greater loads.

Having thus described my invention, what l claim as new and desire to secure by Letters Patent, isz- 1 A spring built up of superposed leaves and formed'ivith a 'thin master leaf and thicker supporting leaves applied to opposite sides thereof.

2. A spring built `up of super-posed leaves and embodying a thin master leaf and thicker supporting leaves on opposite sides .of said master leaf there being more supporting leaves on one side of the master leaf than on the other, .some of the leaves on the former side of the master leaf being of greater lengtht than the longest leaves on the other side of the master leaf.

3. A spring built up of superposed leaves and formed With a thin master leaf and thicker supporting leaves, 'a number of the leaves being originally formed with diierent degrees of curvature so that small internal initial stresses are produced therein il (l When they are clamped together and a counter-spring mounted in cooperative relation with the main spring to take up the rebound. l

L A` spring built up of superposed leaves and formed with a .thin master leaf and thicker supporting leaves, a number of the leaves being formed individually With ferentdegrees of curvature so rthat small internal initial stresses are produced in the master leaf thereinl when the leaves are .clampedf together, in combination with a dif- -similarly constructed counter-spring having" an opposed relation thereto.

5. A spring built up of, superposed leaves and formed with a thin master leaf and thicker supporting leaves, a number of the leaves being individually bent so that small internal initial stresses are produced therein when they are clamped together7 in combination with a' smaller and similarly constructed counter-spring having an Opposed vrelation and mounted with the ends thereof normally spaced from the main spring.

6. A spring built up of superposed leaves and fornied with a thin master leaf and thicker supl'norting leaves applied to opposite sides thereof so that the spring may be safely flexed in opposite directions, certain of the leaves being individually curved so when the spring leaves are clamped to? gether. A

In Witness whereof l have hereunto set my hand in the presence of two subscribing Witnesses.

- DAVID LANDAU. Vitnesses:

C. A. Ion,

' JNO. A. CHAimEs'. 

